Viconics VZ7260(X) VZ7656(X) BACnet Installation Manual - Manual (Page 29)

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Wiring Guide Overview
Viconics uses EIA-485 as the physical layer between their devices and supervisory controllers.
For clarity we will use the term “Device” to represent any product with an active EIA-485 network connection,
including Viconics and non-Viconics controllers.
Summary Specifications:
Parameter Details
Media Twisted pair 22AWG-24 AWG, shielded recommended
Characteristic Impedance 100-130 ohms
Distributed capacitance Less than 100 pF per meter (30 pF per foot)
Maximum length per segment 1200 meters (4000 feet) Note: AWG 18 cable
Polarity Polarity sensitive
Multi-drop Daisy-chain (no T connections)
Terminations 1. Viconics’ devices are installed at both ends of the
MSTP network:
120 Ohms resistor should be installed at each end.
2. A Viconics device is installed at one end of the MSTP
network and a 3
rd
party device is installed at the other
end:
Install an End-Of-Line resistor value that matches the 3 rd
party device instruction regarding the End-Of-Line resistors
3. 3
rd
party devices are installed at both ends of the MSTP
network:
Follow the 3
rd
party device instructions regarding the End-
Of-Line resistors.
Network Bias Resistors 510 ohms per wire (max. of two sets per segment)
Maximum number of nodes per
segment
64 (Viconics devices only)
Maximum number of nodes per
network
128
Baud rate 9600, 19200, 38400, 76800 (Auto detect)
Table 1: Summary of Specifications for a Viconics’ EIA-485 Network